1. Field of the Invention
The present invention relates to test methods for mobile communication systems and, more particularly, to a method of testing the performance and characteristics of an analog base-band (ABB) chipset operated in a base-band frequency domain.
2. Description of the Related Art
In general, digital mobile communication terminals have a chipset, called an ABB chipset, performing a function of converting and filtering intermediate frequency signals and base-band analog and digital signals. Also, this ABB chipset converts an intermediate frequency analog signal into a digital signal in global system for mobile communications (GSM)/enhanced data rates for GSM evolution (EDGE) mode or code division multiple access (CDMA) mode and converts base-band data to be transmitted into an analog signal. This ABB chipset is an essential component of a mobile communication terminal, and its operations should be tested. Due to a difference in test environments, such as a lab test environment or an automatic test equipment (ATE) test environment, and considering test apparatus and economic conditions, there are testing limitations. In a lab test environment, it is difficult to satisfy various test modes because of the high-cost of ATE. In the case of the ABB chipset, various test patterns should be applied, and a large number of additional equipment is required to obtain proper results. Accordingly, it is difficult to satisfy all test modes by the use of an ATE test.
FIG. 1 is a block diagram illustrating a conventional test method of an analog base-band chipset of a mobile communication terminal. Referring to FIG. 1, the analog base-band (ABB) chipset comprises a digital unit 10 generating digital data and performing and processing a digital modulation, multiplexers 30 and 40 determining a test mode according to a test mode selection signal, an ABB unit 20 processing an analog signal, a test data input/output (I/O) terminal TestData in which a test pattern to be tested is input, a test mode selection terminal TestMode for selecting a test mode, and a test control terminal TestCtrl for controlling the test apparatus in selecting the test mode.
The ABB unit 20 includes a digital-to-analog converter (DAC) 21 converting digital data into an analog signal, an analog-to-digital converter (ADC) 22 converting a received analog signal into digital data, an analog filter 23 filtering analog signals, and a codec 24 converting a received digital sound into an analog signal or an input analog sound into digital data.
In the above-mentioned structure, test data is applied by the ATE test, a test mode is determined by the ATE test, and a test control signal is applied externally. Since pins are structured for various test modes and for controlling the test operation, the number of pins is increased, and the complexity of the process is increased. In the lab test environment, there is a limitation such that various test patterns, e.g., the ATE test, are directly applied to an ABB chipset. This means that it is difficult to predict defects of the ABB chipset that may be generated during its manufacturing process. These defects result in high costs and inefficiencies. In a conventional chipset structure, it is difficult to satisfy the desired accuracy and performance of the test operation in the lab test environment as well as in the ATE test environment.